Yarns and fabrics thereof



Dec. 3, 1968 E R 3,413,798

INVENTOR E l TAN ZUR AGENT 3,413,798 YARNS AND FABRICS THEREOF Eitan Zur, Wilmington, Del., assignor to E. I. du Pont de Nemours and Company, Wilmington, Del., a corporation of Delaware Filed Mar. 6, 1967, Set. N0. 621,049 12 Claims. (Cl. 57140) ABSTRACT OF THE DISCLOSURE A composite yarn composed f an inelastic continuous larnent yarn combined With staple bers having specic work-to-break and tenacity values, the continuous lament yarn being visible among, the staple bers in the composite yarn. A knit fabric of these yarns having unique aesthetics, namely, a silk-life appearance and 21 tactility combining worsted-like and Silk-like band.

This invention relates to novel yarns. The invention also relates to novel, pill-free, knitted fabrics, which have a silk4ike appearanee and a highly unusual tactility combining Worsted-like and silk-like band, which are formed from these novel yarns.

A problem encountered in producing fabrics from staple yarns, both natural and synthetic, is that the staple bers in the resulting fabrics have a tendency during use to associate t-ogether in the form of small balls 01' pills which give the fabric an unsightly appearance. Pilling is especially severe in knitted staple fabrics, since the yarns used in knitted fabrics usually have less twist than the yarns used in woven fabrics and fabric construction is generally looser. Synthetic bers of both the acrylic and polyester type are now available in which the toughness of the bers has been deliberately minimized so that pills, when formed, Will break oft rather readily Although the number of pills found 0n fabrics made from such bers is lower than the level previously consiclered normal, some pills are usually seen at any given time after the fabric has been placed in use. Accordingly, a continuing need has been felt for the development of fabrics upon which pills are seldom seen, if ever, and which accordingly could be described as pill-free.

It is an object of this invention to provide nove] yarns. Another object is to provide pill-free knitted fabrics fron1 these novel yarns.

Statement 0f the invention In accordance with this invention, a composite yarn is provided composed of inelastic continuons lament yarn cornbined with staple bers having a work-to-break of less than about 0.5 gm. cm./denier cm., at least 30 wt. percent 0f said staple bers being acrylonitrile polymer staple bers having a tenacity of less than 1.5 g.p.d., the continuous lament yarn being visible am0ng the staple bers in the eomposite yarn.

The novel fabric of the invention is a knit fabric of the composite yarn dened above.

Description 0 the preferred embodiments o the inverztion In one preferred embodirnent of the invention, the yarn is a core-spun yarn in which the staple bers form a sbeath around the continuous lament core, with the continuous lament being off-center and close enough to the side of the yarn that it is visible among the sta-ple bers in the composite yarn. The knit fabric produced from this yarn has a subtle, highly attractive differential luster. Its band, although somewhat silk-like also has a worsted -like tactile impression, all the more surprising because 0f the silk-like appearance of the fabric.

nited States Patent O In another preferred embodiment 0f the invention, the staple bers are twisted in the form of a staple yarn which in turn is ply-twisted about the continuous lament yarn. In this embodiment of the invention, the continuous lament is even more readily apparent than in the corespun yarn. The knit fabric produced from this yarn has a high degree of differentiell luster. Its hand also has a marked worsted-like tactile impression, although the tactility of this fabric is more silk-like than that of the fabric made from the core-spun yarn of the invention.

In a particularly preferrecl embodirnent of the invention, the staple bers in the composite yarn are a blend in which from 30% to 70% of the bers are acrylonitrile polymer bers and the rernaining 70% to 30% are polyester bers.

The knit fabric formed frcrn the novel yarns of the invention may be of any knit construction, but the preferred fabrics are double knit fabrics, since the Silklike differential luster and luxurious tactility reach their optimum in fabrics of double-knit construction.

Yarn according to this invention is illustrated in the attached drawing in which:

FIGURE 1 illustrates a side view of a core-spun com p0site yarn;

FIGUR'E 1A is a cross-sectional view of the core-spun composite yarn of FIGURE l;

FIGURE 2 illustrates a side view of a plied composite yarn; and

-FIGURE 2A is a cross-sectional view of the plied composite yarn of FIGURE 2.

Definition 0 terms The term cornposite yarn as used herein, and generally in the art, refers to yarn composed of two or more yarns cornbined together by core-spinning, plying, wrapping or equivalent methods of ccmbining yarn. Corespinning refers to the process 0f introducing continuous lament to a conventional spinning or drafting frame together with one or more rovings of staple bers t0 pro-duce a composite yarn having the continuous filament a's a core and the drafted rovings as a sheath (note, for example US. Patent 3,017,740 to Humphreys). Plying refers to a method wherein two or more yarns are plied (i.e., twisted together) to form a cornposite yarn. (Note, for example, U.S. Patent 2,656,5 to Jackson.) Wrapping refers to a method wherein c0ntinuous larnent yarn is Wrapped With one or more layers of staple ber yarn. (Note, for example, U.S. Patent 2024156 to Poster.) The term composite yarn is to be distinguished from the term composite ber. One 0r more cf the ber components of the composite yarn may suitably be multicomponent ber, the latter term refers to a ber containing two 0r more ber-forming comp0nents in an eccentric relationship over the cross section 0f the ber and throughout the length of the ber. (Note, for exarnple, U.S. Patent 3,039524.)

The term work-to-break as used herein, and generally in the art, is a rneasure of the amount of work (e.g. grarn-centimeter) necessary to break a ber and is given in units of gram-centimeters/denier centimeter. This term gives tensile strength properties in addition to those speciecl by tenacity which is a. measure of the breaking strength of the ber, i.e. the force (e.g., grams) necessary to break the ber.

The term inelastic used in reference to continuous filament yarn refers to any conventional, tenacious, textile yarn prepared from a synthetic polymer, such as polyesters, acrylonitrile polymers, polyamides, e.g., nylon 6,6, polyolens, e.g., polypropylene, which require a comsiderable force (e.g., greater than about 0.15 g.p.d.) to elongate to a low elongation (e.g., less than about 1%) With permanent deformation occurring at a relatively low elongation (e.g., 5% or less). Although all yarns have some measurable elasticity, the term serves to distinguish conventional textile continuous filament yarns from conventional elastic yarns which requi=re -little force to elongate them markedly and which subsequently retract to their initial length when the force is released.

The term continuous filament yarn as used herein includes both monolament and multilament continuous yarns. A wide range of denier is suitable. A total yarn denier of frorn about 30 to about 60 is preferred (about 40 denier being most preferred) for most end uses.

The term staple ber, as used herein, refers to continuous laments cut or brken into relatively short ber lengths. The length 0f these bers is chosen by reference to the particular spinning system used to prepare yarn from these bers (e.g., if yarn is to be spun on the woolen system, the ber is cut to the staple length of natural W001). A Wide range of denier is suitable. A staple ber denier of from about 2 to about 4.5 is pre ferred (about 3 denier being most preferred for most end uses).

The term acrylonitrile polymer as used herein, includes any long chain synthetic polymer composed of at least 35 (preferably at least 85) percent by weight of acrylonitrile units of the formula in the polymer chain. As is well understood, the term includes the homopolymer of acrylonitrile and polymers of acrylonitrile and monoethylenically nnsaturated monomers po'lymerizable with acrylonitrile. Nonlimitative examples of preferred comonomers include styrene, 2- vinylpyridine, 2-methyl-5-vinylpyridine, 4-vinylpyridine, methyl acrylate, sodium styrene sulfonates, vinylidene chloride, and vinyl acetate.

The term polyester refers to a polycondensation polymer with recurring units of the formula constituting an integral part of the polymer chain. The polyester is preferably a polymer of a glycol and a dicarboxylic acid in which the repeating strnctural units of the polyester contain at least one aromatic nucleus havin-g chain-extending valence bonds separated by a minimum of four nuclear carbon atoms. Nonlimitative examples of preferred polyesters include polyethylene terephthalate alone or as a copolymer with ethylene 5- (sodium sulfo) isophtha'late or ethylene hexahydroterephthalate.

T0 achieve the objectives of this invention the staple bers twisted about the continuous filament yarn should have a work-to-break of less than about 0.5 gm. cm./ denier cm. Staple bers of W toughness are required in the yarns of this invention in order that aggregations of fuzzed staple bers approaching the dimensions of a pill will be sheared off. lt is believed that this occurs as the result of the continuous filament yarn acting as a dull knife blade, although this Statement is not intended as limiting. At least 30% of the staple bers in the composite yarn should be acrylonitrile polymer bers having a tenacity of less than about 1.5 grams per denier (g.p.d.). When a pill begins to form from fuzzed staple bers in a garment, these low-tonghness, low-tenacity acrylonitrile polymer bers break readily and thereby contribute markedly to the elimination cf the pill while it is still small or incipient, by the self-action of the novel yarn. The characteristic desirable aesthetics of acrylonitrile polymer staple bers are imparted to the fabric by the presence of these bers to the extent of at least 30% among the staple bers. Preferably, acrylonitrile polymer bicornponent staple bers having a work-tmbreak of less than about 0.5 gm. cm./denier cm. and a tenacity of less than 1.5 g.p.d. are used. These bicomponent bers impart increased bulk to the fabric, which enhances the luxurious tactility of the fabric.

If desired, all of the staple bers may be acrylonitrile polymer staple bers; however, up to 0f the staple bers may be polyester staple bers or other staple bers so long as their work-to-break -does not exceed 0.5 gm. cm./denier cm. The tenacity of these bers may be higher than the tenacity of the acrylonitrile polymer bers, and if so the acrylonitrile polymer bers may break first in incipient pills to weaken their attachment to the fabric, but the -low toughness of any remaining bers leads to early elimination of pills by the self-action of the novel yarn.

It is important that the continuous filament yarn be visible (i.e. that it show through and be visible to the unaided human eye among the staple bers) in the composite yarn; so that the continuous filament yarn is not completely covered. This is believed to be an important factor in the silk-like appearance, as well as the imp=roved pill resistance, of the |knit fabric. The methods for preparing Composite yarn (previously mentioned) must be practiced nnder conditions which provide this incomplete cover. In plying, the twisting together of the yarns generally results in the continuous filament being visible. In core-spinning a small displacement of the continuous filament yarn frorn the edge of the staple ber roving as it is fed into the spinning frame Will generally result in the incomplete cover. In wrapping, it is necessary to incompletely wrap the continuous filament yarn with staple ber yarn (i.e., allow intermittent portions of the continuous filament yarn to be left uncovered).

Composite yarn having these characteristics is illustrated in the drawing:

In FIGURE l, a core-spun Composite yarn 10 is illustrated. The continuous filament yarn 12 is the core with a sheath of staple bers 14. The continuous filament yarn 12 is off-center and closer to the side of the composite yarn 10, and is visible among the staple bers 14.

In FIGURE 2, a plied composite yarn 20 is illustrated. The continuous filament yarn 22 is t-wisted together with the staple bers 24 in a ply formation, i.e. neither is wrapped a s a cover about the other as a core but rather both follow. generally similar paths about each other. The continuous filament yarn 22 is visible among the staple bers 24 in the Composite yarn 20.

The relative weights of continuous filament yarn and staple ber may be varied in the Composite yarn to provide different degrees of cover, resulting in variations in the tactility and luster of the knit fabric end prodnct. Increasing amounts of continuous filament yarn generally results in a more silk-like tactility as well as a more silk-like luster. Decreasing amounts in turn result in these properties =being more worsted-like. The continuous filament yarn must be present to provide improved pill resistance. For most purposes to achieve a unique balance of silk-like and worsted-like properties from about 10 to about 40 weight percent of continuous filament yarn is preferred. A most preferred range is from about 10 to about 30 weight percent. As is evident frorn the above dis cussion, one skilled in the art may vary these percentages for various end use requirements.

EXAMPLES The preferred embodiments of the invention will be illustrated by the examples that follow. Parts and percentages are by weight unless otherwise indicated.

EXAMPLE I This example illustrates a preferred core-spun yarn and knit fabric according to this invention.

A roving comprising a blend of equal Weights of staple bers is prepared from the following starting materials:

Fiber A.A bicomponent acrylic ber in which the components are a mixture of polymers, the first of which has a composition of 95.25 wt. percent acrylonitriie, 3.25 Wt. percent sodium styrenesulfonate and 1.50 Wt. percent methyl acrylate, and the second component has a composition of 99.29% acrylonitrile, 0.22 wt. percent methyl acrylate, and 0.49 Wt. percent of sodium styrenesulfonate.

The fibers have a denier per filarnent of 3.5, a tenacity of 0.94 g.p.d., an elongation of 43.7%, a toughness (Workto-break) of 0.39 grn. crn./denier cm., and are in the form of a tow of about 470,000 denier.

Fiber B.A polyester fiber of polyethylene terephthalate/5-(sodium sulfo)isophthalate (98/2) having a relative viscosity of about 12. The fibers have a denier per filament of 3.0, a tenacity of 2.2 g.p.d., an elongation of 25%, a toughness of 0.35 gm. cm./denier cm., and are in the forrn of a tow having a denier of about 470,000.

The roving is prepared by feeding two ends each of the Fiber A and Fiber B tows to a Pacific Converter and cutting them to a vari-cut length of 4.5 inches (11.4 cm.) to forrn a. sliver, which is then blended by pin-drafting and formed into a one-hank roving on a conventional worsted system.

The roving so prepared is core-spun with a continuous filament yarn designated as Fiber C and more fu1ly identified as follows:

Fiber C.A bright, 40-denier continuous filament polyethyiene terep-hthalate yarn having a relative viscosity 01 about 28 and comprised of 8 filarnents. In contrast to the 10W toughness of the polyester fiber designated above as Fiber B, typica1 va1ues for this poiyester fiber are a Workto-break 0f 0.75 grn. cm./denier cm., a tenacity of 4.6 g.p.d. and an elongation of 30%.

In preparing the core-spun yarn, the roving is given a draft of 17.77 on a spinning frame Set t0 give a 1/40 worsted count yarn having a Z twist, and the filament yarn (Fiber C) is fed about 0.125 inch (0.318 cm.) to the 1eft of the 1eft edge of the roving at the delivery roll. The roduct is a 1/33.3 worsted count yarn having a denier of 239 and composed of 42% by weight of the acrylic sheath fibers (Fiber A), 42% of the polyester sheath fibers (Fiber B), and 16% by weight of the continuous fi1ament polyester yarn (Fiber C). The presence of the continuous filament yarn in the resulting corespun yarn is readily apparent, since it is on1y partially hidden by the staple fibers in the sheath. The yarn has a Lea Product of 2165 and a Coefiicient of Variance of 15.0%.

The sheath-core yarn so prepared is knit on an l8-cut Dubied Wevenit circular weft knitting machine using a Swiss Double Pique stitch. The knitted greige fabric has a weight of 9.6 ozs./sq. yd. (325 grams/sq. meter) after stearning. Excellent knitting performance is observed.

The knitted fabric is heat-set on a frame in 350 F. air under tension for an exposure time of 2 minutes. The fabric is then scoured and dyed according to the following procedure, in which all percentages are based on fabric weight. The scouring is carried out in an aqueous 1.0% solution of nonionic detergent for 15 minutes at 160 F. (71 C.). The dye solution, at a 40:1 bath to fiber ratio, comprises 0.03% sodiurn acetate, 0.5% of the nondonic detergent, 20.0% sodium suifate, and 1.5% of C.I. (Colour Index) Basic Red 22 dye. The dyebath is adjusted to a pH of 4.5 with acetic acid, the temperature is raised to 212 F. (100 C.), and the fabric is dyed for 30 minutes. The dyebath is then cooled and 0.46% of C.I. Disperse Yel1ow 54 dye, 0.01% of C.I. Disperse B1ue 61 dye, and 2.5 grams/liter of dispersed butyl benzoate are added. The pH is adjusted to 7.0 With tetrasodium pyrophosphate, the bath is again heated to 212 F. (100 C.), and dyeing is carried out for an additional hour. The fabric is then removed from the dyebath, rinsed, tumble dried at 180 F. (82 C.), stearn calendered about 5% over the as-dryed width, and serni-decated with a 1-minute exposure to steam and a l-rninute exposure to vacuum.

The dyed and finished fabric has a 1uxurious difierential 1uster, quite un1ike knitted fabrics of conventional staple b1end yarns. The fabric has unusua], highly luxurious aesthetics characterized by a high degree of liveliness, excellent drape, and tactility combining worsted-like and silk-like band. The fabric performance in wear is outstanding and is characterized by no detectable pilling, after 200 hours of wear, in a dress made of the fabric. When the dress is worn 200 hours With five total dry cieanings (every 4050 hours), the fabric appears virtually unchanged With respect to the fabric in a similar dress of the sarne material which has never been worn.

The pilling propensity of the dyed and finished fabric is evaluated on the Randorn Tumble Pilling Testet described by E. M. Baird, L. C. Legere, and H. E. Stanley in Textile Research Journal, v01. 26, pages 731735 (1956). The following scale of pil1 1evel ratings is employed in evaluating fabrics in this test:

5.0n0 piiling 4.0-siight pilling 3.0-moderate pilling 2.0heavy pilling 1.0severe pilling Intermediate ratings Within the above values are assigned to the nearest 0.1 unit to place fabrics in their proper rank in the above scale. Three samples of each fabric are rated, and the ratings are averaged.

The dyed and finished fabric of the example, designated as the Test Fabric, is compared with a Control Fabric double knit from a yarn composed of staple fibers only, prepared from a blend of equal weights of Fiber A and Fiber B. The weight, construction, dyeing, and finishing of the Control Fabric are sirnilar to those of the Test Fabric. The results are as follows:

Random tumble pill test rating 3 min. 5 min. 10 min.

Test Fabric s. o s. 0 5. 0 Control Fabric 4. 4 4. 3 4. 5

EXAMPLE II This example illustrates a preferred plied yarn and knit fabric according this invention.

A quantity of the roving of Example I is spun into a 1/40 worsted count staple yarn having a 15 Z twist, a Lea Product of 1560, and a Coeflicient of Variance of 17.7%. The compieted staple yarn is ply twist6d at the twister together with the continuous filarnent polyester yarn designated -as Fiber C of Example I. The yarn is plied to achieve a balanced twist, requiring approximately 4 S twist. The plied yarn so produced is a 239 denier, 1/33.3 worsted count yarn having a Lea Product of 2340 and a Coeflicient of Variance of 16.7%. The presence of the continuous filament yarn in the plied yarn is readily apparent.

A double-knit fabric is prepared from the plied yarn, following the procedure of Example I, except that the knitted greige fabric has a weight of 8.3 ozs./sq. yd. (281 grams/sq. meter) after steaming. The knitted fabric is heat-set, dyed, and finishecl in the Same way as the knitted fabric of Example I, except that in the dyeing step the fo1lowing basic dyes are substituted in place of the basic dye employed in Example I: 3.34% C.I. Basic Blue 35 dye, 3.34% C.I. Basic Blue 21 dye, 0.786% C.I. Basic 7 Yellow 15 dye, 0.607% C.I. Basic Red 18 dye; while 0.46% C.I. Disperse Yellow 54 dye is again used and the amount cf C.I. Disperse Blue 61 dye is increased to 2.53%.

The knitted fabric so prpared and finished has a high degree of dilferential luster, more pronounced than the luster of the fabric of Example I. 'I'he fabric is very lively and has excellent drape, being in this respect very similar to the fabric of Example I. The tactility of the fabric combines both worsted-like and silk-like band; with respect to the fabric of Example I, it is somewhat more silk-like. The fabric erformance in wear is outstanding and is characterized by no detectable pilling, after 200 hours of wear, in a dress made of the fabric. When the dress has been worn 200 hours With ve total dry cleanings (every 40- 50 hours), little difierence is observable between the dress which has been worn and a similar dress which has rrever been Wrn.

The knitted fabric, after nishing, is given ratings of 5.0 on the Random Tumble Pilling Tester after test periods of 3, and minutes, correlating With aetual wear performance similar to that of the Test Fabric of Example I and up to 0.5 unit higher than the Control Fabric ratings during actual wear. These results further conrm the additional importance of the required continuous filament yarn.

As the examples illustrate, the performance in wear of the knit fabric is outstanding, and is characterized by 110 detectable pilling after 200 hours of wear in garment form. Garments of the fabric, worn for 200 hours With five total dry cleaning-s (every 4050 hours), are rernarkedly fresh looking and difcult to distinguish from unworn garments. The signicant effect of the presence 0f continuous filament yarn 0n pilling is clearly shown. Most surprising, however, is the unexpected appearance of the fabrics with their silk-like differential luster; their excellent drape and liveliness; and especially their unusual tactility, or band. The band of the fabrics is characterized by a marked worsted-like tactile impression, very unlike that of conventional knitted fabrics. The hand is perhaps best described as intermediate between silk-like and worstedlike.

The -great and varied utility for these novel yarns and fabrics will be obvious to those skilled in the art.

T-he foregoing specification is intended to be descriptive of the invention, but due to the possible variations it is not in limitation thereof. The scope of the inventiou is de fined by the following cla.ims.

What is claimed is:

1. Composite yarn comprising inelastie eontinuous lament yarn combined with staple bers, said staple bers having a work-to-break of less than about 0.5 gram-eentimeter/denier-centimeter, at least about 30 weight percent of said staple bers being acrylonitrile polymer staple bers having a tenacity of lass than about 1.5 grams per denier, the said continuous filament yarn being visible among said staple bers in said composite yarn.

2. Core-spun composite yarn according to clairn 1.

3. Plied composite yarn according to claim 1.

4. C0mposite yarn according to claim 1 wherein said cor'1tinuous filament yarn comprises from about 10 to about 40 weight percent of said composite yarn.

5. Composite yarn according to elaim 4 wherein said eontinuous lament yarn weight percent is lese than about 30.

6. Composite yarn according to claim 1 wherein said eontinuous filament yarn has a total yarn denier of from about 30 to about and said staple ber has a ber denier of from about 2 to about 4.5.

7. Comjaosite yarn according to claim 1 wherein said staple bers are a blend in which from about 30 to Weight percent are acrylonitrile polymer bers and 70 to 30 weight percent are polyester bers.

8. Composite yarn according to claim 1 wherein said acrylonitrile polymer eontains at least weight percent of recurring acrylonitrile units.

9. Composite yarn according to claim 1 wherein said acrylonitrile polymer staple bers are multic0mponent bers.

10. Composite yarn according to claim 1 Wherein said continuous filament yarn is prepared from a synthetic polymer selected from the group consisting of polyesters, acrylonitrile polymers, polyamides and polyolens.

11. Knit fabric eontaining the composite yarn -of claim l.

12. Double knit fabric containing the composite yarn of claim 1.

References Cited UNITED STATES PATENTS 2,890,567 6/1959 Taylor et al. 57-140 3038295 6/1962 Humphreys.

3081516 3/1963 Evans 57-l40 3,365,875 1/1968 Hall 57-140 XR FRANK J COHEN, Primary Exzzmz'ner.

D. WATKINS, Assz'sfant Exa=miner. 

